FIGURE 6.

Mouse brain GP-NAE phosphodiesterase and GDE1 display similar biochemical properties. A, pH rate profile of brain membrane GP-NAE phosphodiesterase (open diamonds) and membranes from COS-7 cells transfected with GDE1 (filled squares) showing equivalent pH optima. Assays were performed in buffer containing 50 mm Tris, 50 mm HEPES, and 50 mm glycine and adjusted to the desired pH with HCl/NaOH. B, mouse brain GP-NAE phosphodiesterase and GDE1 display similar cation sensitivity profiles. Mouse brain membranes (open bars) and GDE1-transfected COS-7 cell membranes (filled bars) were treated with 2 mm CaCl₂, ZnCl₂, MgCl₂, or EDTA. Assays were performed with 100 μm [1′-¹⁴C]N-C16:0 GP-NAE substrate, where the release of [1′-¹⁴C]N-C16:0 NAE was measured by thin layer radiochromatography.